To determine how well staples can satisfy energy and protein needs of infants who are: 1) healthy, 2) convalescing from malnutrition, 3) recovering from diarrhea, or 4) severely malnourished. Limitations to intake imposed by: a) bulkiness, b) carbohydrate and protein digestibility, c) protein content and quality, and d) effect on absorption of dietary fat. Wheat, as pasta, and white potato, boiled and mashed, will be studied independently, by balance technique, in diets of 9 healthy 4-month old and 9 convalescent malnourished 6-24 month old infants; 6.4% of diet calories as protein and 25% as 20-80 mix of cottonseed-soy oils. Staple to provide approximately 67, 44 and 22% of calories and 100, 67, and 33% of protein in pre-ordered varied sequence during 9-day periods, each preceded and followed by 9-day period without staple. In all, casein to provide balance of protein and sucrose balance of carbohydrate. Time required to feed diets; stool wet and dry weight, fat, nitrogen and energy (bomb calorimetry); urine nitrogen will be measured. Plasma free amino acids in fasting state and 3 and 4 hours post-prandially for each diet. Maximal proportions tolerated and utilized will be fed to 4 convalescent infants for 90+ days to study growth and digestive adapatibility, to 6 infants recovering from diarrhea, and 6 severely malnourished but not acutely ill. Metabolic collections to study digestibility and utilization in these situations. but